


Breathless

by Interverse



Category: Undertale (Video Game)
Genre: Alternate Universe - Swapfell (Undertale), Alternate Universe - Underswap (Undertale), Light Angst, M/M, Meaning That It Isn't Explicitly Given but Stretch Obviously Likes It and Would Have Said Yes, Mildly Dubious Consent, Somnophilia, Sub Slim, Vaginal Sex
Language: English
Status: Completed
Published: 2020-04-27
Updated: 2020-04-27
Packaged: 2021-03-01 19:26:22
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,784
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23872321
Author URL: https://archiveofourown.org/users/Interverse/pseuds/Interverse
Summary: After waking from a nightmare, out of breath and feeling broken, Slim remembers something. This wasn't his bed, but his partner's, and that very monster was still sleeping it in right next to him.
Relationships: Honeybbq - Relationship, Papyrus/Papyrus (Undertale), Underswap Papyrus/Swapfell Papyrus
Comments: 4
Kudos: 35





	Breathless

**Author's Note:**

> This is a reupload of an old story that was originally in a collection of oneshots, now heavily edited.

Skeletons don’t exactly have lungs. This is strange, considering they have the need to breathe air just like all monsters and humans and many other creatures, but their anatomy made do. Intakes of air filled the magic in their throats and their ribs, so the visual was similar in how their ribcages would rise and fall with their breaths.

Unfortunately, this also meant they could suffocate, drown, dust from a lack of air to keep their magic flowing. Slim couldn’t tell what it was this time. Was it a hand, clamping down on his cervical vertebrae in an attempt to wrestle the life out of him? Was it water, hot and vast and invading and wrong as it rushed into his mouth and filled his body despite his lack of consent? Was it a material, stretched taut over his face and muffling his screams as he desperately tried to tear the offending barrier away with trembling hands? Or perhaps it was nothing but himself. His doubts, his fear, his shortcomings materializing and swelling in his throat until he had no more room to suck in the breath that he foolishly thought would chase his problems away.

No. It was none of those things. It was nothing but a paralyzingly real fabrication of his own hated mind. He woke, tongue curling out of his mouth as he desperately sucked in a breath, rattling his ribcage and sending tremors down the length of his body until he collapsed back down onto the bed, breath rushing out from between his teeth along with a noise somewhere between a cough and a sob. He squeezed his sockets closed, drawing another breath and then another, repeating the process until his Soul had slowed to a rate leisure enough to feel like it wasn’t ramming against the inside of his sternum in an attempt to escape the unkempt prison that was his body.

Slim didn’t know why a common theme of his nightmares was breathlessness; always being smothered or drowned or choked by whatever his sleeping mind decided to force upon him. Perhaps it was because he felt trapped in life, perhaps it was due to some other philosophical cause, or perhaps it was meaningless, and just so happened to be that way for no reason in particular.

He raised a hand to his neck and pressed his clawed fingertips into one of the dips between his vertebra to feel as the bones and cartilage shifted, expanding and shrinking ever so slightly with his breaths. He did this to convince himself that he was really breathing, because numbness was something else he often found himself with. All the smoke didn’t help with that either, but blunting his unwelcome emotions and replacing them with ones less burdening had become his favorite coping mechanism, if it could even be considered one. He gently compressed his hands into fists, feeling his claws dig into the old, soft fabric of the jacket he had yet again fallen asleep in. He smiled slightly at all the memories of his brother telling him to wash it, then resorting to bargaining and eventually literal begging when he disregarded the order.

Slim wondered what Black was doing now. He didn’t know what time it was, because he was certainly not in the mood to turn to look at the clock, but the room was dark. Therefore, by the process of elimination, his brother was probably sleeping, most likely recovering from a week of his work as Captain; an extremely demanding position. When he woke up, maybe he’d take some time to himself for once, or go visit one of his friends like Comic, or Blue

And with that, he finally remembered he wasn’t in his own bed. Slim honestly had no idea why he always failed to remember when he was spending the night with his boyfriend, but the realization gave him enough motivation to wiggle about until he was resting on his side, facing the other skeleton. Stretch was still fully within the grasp of sleep, curled up in a little ball of bones and orange fabric that made him look much smaller than he was. 

But Slim felt even smaller, somehow, insignificant and isolated in his tangle of blankets. Stretch was breathing steadily, spidery fingers curled into loose fists just beneath his chin as a look of simple serenity rested upon his features. Slim felt his Soul flutter at the sight of the other skeleton at peace. His features were soft and beautiful, far more sightly than the sharper structure of Slim’s face, and freckles of shimmering marigold magic were scattered across his cheekbones and nasal ridge. The monster huffed in his sleep, nuzzling into the pillow beneath his head and then seeming to deflate into the bed with a drawn out sigh. Slim wrestled one of his arms out from beneath the blankets, then reached out with the advantage of his long limbs and gently pressed his hand to the side of Stretch’s face, rubbing soft little circles into the skeleton’s temple with his fingertips. He needn’t worry about waking his partner, for he was about as hard to wake as a rock, so he continued with the lingering touches until the need for this perfect monster grew too strong for him to remain so inactive.

It might not have made that much sense, then, that Slim stopped touching his companion altogether, but some type of logic returned to his actions when he began to touch himself instead. He wound his slender fingers through the hoops of his ischium and thumbed at his pubis, exhaling and squeezing his legs together at the ticklish touches. Why was it that he always felt so needy upon waking? It was as if spending so much time unattached from reality with only himself for company flipped a switch inside of him that made him crave physical contact more powerfully than all other times of the day. He usually resorted to spooning with his bedding and touching himself after he had escaped the confines of sleep, but since the birth of his relationship with Stretch, he was quite a help in his times of need whenever they ended up sleeping in the same bed. At first just with cuddles and kisses, which was more than enough, but after a while until they had both grown comfortable enough with each other, with more intimate activities.

It appeared today was one of those days. Slim usually resorted to touching his pelvis, because the bones there rarely received attention and it felt the most intimate, but it didn’t always have to involve any magic or sexual pleasure. However he felt himself warm under his fingers before long, shivering when his magic began to grow restless just beneath the surface of the delicate bones. A few more minutes of the slow, lazy touches and the magic emerged from his body, gathering in a small little mass at his pubis. He gently prodded at it with his index and middle fingers, breath hitching at the little tingles the contact slowly spread around his pelvis. The magic lazily began to shape itself, and Slim gripped it around its middle to gave it a small squeeze, curling his toes in preparation before dragging his hand up the length of it and thumbing at the very tip where a small, sensitive slit had appeared. He made a weak little noise at the back of his throat, slipping his hand down to the base of his cock and squeezing the other one into a fist against his sternum. It only took a few more moments of timid touching to have precum seeping from his fragile body, but Slim was tiring of having to move his wrist so much.

He chose to solve this problem by forcefully collapsing the magic back down against his pelvis and putting more thought into the process when he re-formed it. He pushed his hand further between his femurs and pressed his fingers against the new manifestation of his magic, sighing at the soft warmth against his bones. The stiffness of the magic from before had been converted into moisture, greeting his fingertips when he pushed them down between his inner labia. He drew his hand away a bit and pinched one of his lips, feeling the magic easily shy away from between his fingertips with the slickness of his phalanges. With a sigh, Slim pressed one of them up against his clit, shifting as he stroked at the sensitive bit of ectoflesh until it had grown fully swollen from his attention to the spot. He slipped his fingers down along his magic, pressing a few of them against his entrance and shivering at the warmth radiating from the area. He couldn’t exactly push them inside since there was no magic to slip within so he slowly forced his magic into a full body with a heavy breath, shifting his hand into a more comfortable position now that it was compressed more tightly between his summoned thighs.

Once he was at an angle where he was able to, he dipped a couple of his fingers into himself and spread them apart until his magic fought back against the pressure. With a small shiver, Slim brought them back up and pressed them against his clit, spreading the viscous little strands of his arousal he had picked up over it and earning a small twitch from the sensitive bundle of magic. Back down his fingers went, then inside of him to the second knuckle before he curled them upwards to massage at a sensitive spot along his inner walls. He whimpered quietly, then pressed his hand flat over himself, grinding his palm against his lips and clit with a small noise.

He quickly came to the realization that he was not enough to satisfy himself, and he bit the inside of his cheek in indecision. He had been planning to wait for Stretch to wake as he usually did if he was bothered with a series of small noises over a long enough period of time, but waiting was becoming more and more unappealing to Slim with every passing moment. He would probably be able to completely lift Stretch from the bed without waking him if he were strong enough, and the prospect of messing with him without his knowledge or explicit consent made Slim feel creepy as all hell. But… would he really mind? Or maybe it didn’t matter because Stretch could awake long before Slim managed to force his magic to form anything in order to tell him to stop or keep going.

Slim’s neediness won over his better judgement despite the many problems with the situation, so he pulled his hand away from his magic and brought it to his face instead, then shyly licked it clean before wriggling into a sitting position. He slipped his jacket from his shoulders and closed the small distance between him and the other Papyrus; then, wincing at his actions, pulled the blankets away from Stretch’s sleeping frame. He was wearing nothing but his offensively orange sweatshirt and Slim was now outfitted similarly, only left with the same dark purple sweater that he wore nearly every day. He slowly disentangled his boyfriend’s limbs from one another, baffled at how the guy was able to sleep comfortably in such a position. His knees had been pressed up to his chest, and his legs were crossed. One of his arms had been looped under his knees while the other was in a relatively normal position, save for the way his wrist practically wound around the other in order to give the illusion that his hands were casually beneath his chin despite the chaos that had been concealed under the covers. Once he had managed to nudge Stretch onto his back, arms and legs laid flat on the bed, Slim shuffled between his companion’s femurs and set to work, curious to see how his decision would play out.

He gripped onto Stretch’s iliac crests, massaging them and exhaling shakily, purposefully angling his head so that the warmth of his breath billowed out against his partner’s pelvis. The lack of reaction combined with Slim’s rapidly increasing impatience had him dipping his head down to hesitantly press his tongue up against Stretch’s pubis before long. He let it rest there for a moment, then stuck it out further and coiled it around the small, delicate bones and closed his mouth against them as well, suckling gently and doing his best to keep a steady pushing and pulling motion up with his tongue. He apparently did this well, because he was rewarded a bit later with warmth against his mouth. Slim hummed in approval, the vibrations the sound made finally earning him a reaction from the other skeleton in the form of a small whimper.

Slim pulled away from the bones with a labored breath but didn’t leave them unattended, replacing his mouth with his fingers. While this left Stretch without the wetness and warmth he’d had earlier, Slim was able to touch him with more precision now, and to his delight, a small bit of marigold magic swelled into his touches. He sped his fingers up, excitement fizzling in his Soul, and was gifted a greater volume of the magic, which he abandoned briefly in his eagerness to lap at it in place of the other touches.

He let out a small, tentative moan into the magic, then another when he felt it pulse under his tongue in response. It started to form, slowly at first, but then more rapidly until Slim had to pull back to retain his ability to breathe. Once the magic had settled, Slim suckled on it a few times before taking it from his mouth and instead lovingly holding it with both of his hands. He gazed down at Stretch’s familiar length, almost content to simply sit there in awe of the monster before him as festered in his love and arousal, but his own needs were too nagging to ignore without discomfort. Slim shuffled until he was straddling Stretch’s pelvis, whimpering and grabbing the other monster’s cock to hold it upright. He had managed to dribble down one of his own thighs, the realization plenty to have his cheeks warming with a plum toned blush. With a breath, he lowered himself just enough to let the tip of his boyfriend’s magic spread his labia apart, but no further, just taking a moment to quiver and grip the other’s pelvis with his conjured thighs. He moved his wrist, rubbing Stretch’s magic along his until it brushed against his clit. He mewled weakly before gathering the strength to rock his hips, grinding the sensitive nub of magic over the head of Stretch’s cock as gently as he could manage, but his impatience showed itself when he moved fast enough to disconnect them.

Slim lined their magic up and sat down, slowly at first, then more quickly with a long overdue moan. He hunched over, panting weakly once he had hilted himself on the other’s length, feeling the tip prod into the back of his magic. His desires satiated at least for a second, Slim took a moment to get into a more comfortable position. He spread his knees further apart, eyelights rolling back in his head and a low groan escaping his throat when Stretch’s magic consequently jabbed into his more sharply, then reached forward with one hand and pressed the palm of it against one of his boyfriend’s bottommost ribs to steady himself. He glanced up at Stretch’s face for the first time in a while, eyes having previously been locked in other places. He was more expressive now, browbones furrowed just the slightest bit with a small blush beginning to surface on his cheekbones and nasal ridge.

With a whimper, Slim rocked his hips, his jaw falling open to let out a shallow pant as soon as he felt his counterpart’s magic shift within his. He continued, slowly but firmly grinding himself down on Stretch’s cock and moving his other hand to slip a finger onto himself with a noise that could be described as nothing else than completely pathetic. Slim paid it no mind, circling his clit with a fingertip and then two, speeding up his grinding as the ache in his core bloomed outward until he could focus on little else. He abandoned the motions after a few minutes, instead rising on Stretch until he was about halfway empty of the other monster before sliding back down much more swiftly, squeaking and then muttering a quiet curse to himself in his embarrassment of the noise.

But he didn’t let that hold him up, for the feeling of fullness - both in his body and his Soul - was too intoxicating to steer his focus from. Stretch’s magic massaged his insides and his fingers, though shaky, managed to stay moving on his clit consistently enough to keep him motivated despite the exertion the position required. He panted and whined and moaned, and was distantly reminded of his dreams. Perhaps being breathless wasn’t always a bad thing.

Slim’s excitement flared hotly when Stretch twitched inside of him, pulling a high wine from his mouth and setting him trembling. He managed to sink and fall on Stretch’s cock a few more times before his movements grew too sloppy to keep the motion up, and instead resumed in his grinding, albeit much more quickly. He pressed against his clit so firmly that the throbbing bit of magic slickly slid between two of his fingertips and he opted to hold it there, for he knew he only had a few seconds of coherent thought left to his name. As anticipated, his movements were shortly coming to a screeching halt as he coughed out a strangled moan and clamped down on Stretch’s magic as sensation welled and then burst inside of him. His walls loosened around his partner’s length before gripping right back on twice as hard, and that finally had Stretch’s eyes flying open.

He looked confused for a moment, but the realization that he was currently hard and buried deep inside his climaxing boyfriend must have hit him square in the jaw just a second later, for he was suddenly blinking the haziness out of his eyelights and hissing out a stream of curses as his hands instinctively flew to grip onto the other skeleton’s hips. Slim sobbed out another moan at the contact, allowing both of his arms to fall limply to his sides as he sat upon the monster he loved, staring into his bright and glimmering eyelights with his own, unfocused and blown wide. It took a while, but his orgasm faded and the contractions of his magic slowly lessened in frequency until both finally came to an end, and Slim weakly deflated atop the other monster with a low whine.

“H-Hell, love, why didn’t you wake me?” Stretch stammered after a few moments, the first to speak.

Slim swallowed, then sucked in a breath in order to reply. “I uh… I guess I did..?”

“Well yeah, but not after… uh… this…” Stretch’s eyelights flicked down to where their magic met.

Slim weakly raised an arm to cover his eyes with a sleeve in his embarrassment. “I’m… I’m sorry…”

“No, it’s okay…” Stretch murmured quietly. “Ah, what’s the occasion?”

“I um… I dunno…” Slim mumbled, lowering his hand again. “You just looked really… happy… in your sleep… and that made me happy too, so for some reason I decided to- to ride you in your sleep? What the fuck??” When forced to explain his actions, they suddenly made a lot less sense.

“Ha, what the _fuck_ indeed.”

And then Slim was laughing, but the sound was cut off with a gasp when one of Stretch’s hands left his hip and lowered a bit in order to stroke a finger over his clit. “But what’s on your mind for now, honey?” Stretch asked lowly, sending a shiver through his body.

His options of what to think were severely limited now with the new and not at all subtle touch, but Slim certainly didn’t mind. “I’m thinkin… maybe I should help ya cum too, because it would be quite the dick move to leave you hangin after being the one to force all this…”

A corner of Stretch’s mouth raised in a smile. “That sounds about right. C’mere.” He pulled forward on the summoned hip he was still holding.

Slim happily lowered himself down onto his lover, nuzzling into his neck and winding his arms around his ribcage. He was not given the chance to start moving again, because as soon as he had settled against Stretch’s body, his alternate was quickly returning the embrace and then flipping him over. Slim yelped when his back hit the mattress, but the sound was swallowed by a kiss as soon as Stretch settled over him. Slim moaned against the other monster’s mouth, parting his teeth without hesitation when Stretch licked at him and sighing at his companion’s familiar taste.

Stretch broke away after a moment, and placed another soft kiss on Slim’s nasal ridge before speaking. “Figured this’d be more comfortable for you.”

“Y-Yeah…” Slim breathed, adjusting his hold on his counterpart and letting his head thump down against the mattress.

Stretch noticed and seemed displeased by this, slipping a hand out from beneath him and grabbing a pillow before dragging it over to his skull. Slim smiled, Soul filling with love at the caring action, then lifted his head to allow his partner to nudge the pillow beneath it. He rested back down upon it, then with a small smile, lifted his legs and wrapped them around Stretch’s waist. They were both thin and the length of their limbs was nothing to scoff at, so Slim was able to grip onto the other skeleton quite effectively this way. Stretch grunted in surprise, then returned his smile and used his newly freed hand to snake between their bodies and roll Slim’s clit around in his fingers.

He moaned weakly, pulling Stretch down for a kiss but then breaking from it to let another noise out when the other monster thrusted shallowly into him. Stretch grunted as well, his face warming as they made eye contact. “Love you…” he groaned with the next of his thrusts.

“I love you too, so quit it with the conversation and fuck me…” Slim panted, digging his claws into Stretch’s spine with a whimper.

Stretch dipped down and ran his tongue along Slim’s neck, hot breath billowing out against the magic flushed bones. “I can do that.”


End file.
